1. Field of the Invention
The present invention relates to a vehicle seat such as an automotive seat, having a lumbar support device provided therein, and in particular to a structure of a foam cushion member and trim cover assembly in that kind of seat.
2. Description of the Prior Art
With the recent increased technical develpment, the vehicles seats including automotive one have been improved in many ways in consideration of seating preferences and slightly different best seating postures of individual occupant sitting on the seat.
In particular, among various seats with a lumbar support device, two typical types have been found as conventional seat of this kind, for instance: One is a generally known type according to which the lumbar support portion of the seat is adjusted its cushioning effect by the forward and backward movements of the lumbar plate being controlled by the external knob, and the other is known from U.S. Pat. No. 3,973,797 in which the lumbar support portion of cushion member as well as the trim cover assembly thereon are raised or lowered by the pressing means provided within the seat.
However, those prior arts have been found defective in that, the former does not provide a positive supporting function because of its structure directed to the adjustment of hardness of the cushion member for variable cushiony effect, while the latter, although certainly having a sufficient supportive function because of its pressing means, is yet deficient in the facilitation of smooth displacement of the lumbar support portion against the surrounding areas in the seat, which is also the case in the former prior art. This is attributed to the continuous and integral formation of the lumbar support portion with the surrounding areas in the cushion member as well as in the trim cover assembly, and consequently, the lumbar support portion is not so fully raised as it should be by the forward pushing action of the pressing means. Accordingly, those two prior arts remain to have a poor operationability for effective lumbar support adjustments.